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States and changes of state

Why does ice melt but stay water?

Predict what the thermometer will do, then heat one block of ice until it melts and boils away. Read the thermometer every 30 s, plot your own heating curve, and watch the same molecules change their arrangement.

Ice melting in a glass of water beside a T-shirt drying in the sun.

Choose a module in the contents to start reading, or open a part below.

In this module

  1. Same water, three states

    Properties and particles of solids, liquids and gases

  2. Where does the heat go?

    Melting, boiling, evaporating and the heating curve

  3. Cooling it back down

    Condensing, freezing and the cooling curve

Syllabus statements for this topic · for teachers · 8 statements

Core for every pupil · Supplement also for Extended entry. Paraphrased from the Cambridge IGCSE Chemistry 0620 syllabus (2026–2028); check the official syllabus for exact wording.

1.1 Solids, liquids and gases

Covered in States and changes of state, Gases under pressure

  • 1.1.1Bulk behaviour: solid, liquid, gasC
  • 1.1.2Particle spacing, order and movementC
  • 1.1.3Melting, boiling, evaporation, freezing, condensationC
  • 1.1.4Gas volume with temperature and pressureC
  • 1.1.5Particle explanations; heating and cooling graphsS
  • 1.1.6Particle explanation of gas-volume changesS

1.2 Diffusion

Covered in Diffusion

  • 1.2.1Random motion and net diffusionC
  • 1.2.2Molecular mass and gas diffusion speedS

Cambridge IGCSE 0620 · 24 of 51 modules ready